I've interviewed on two separate occasions with Amazon, but in different areas and both for technical sourcer positions.
Current position, I'm at 4 interviews all via phone and next step is face-to-face. Previously, it was 6 interviews (2 phone, 2 video and 2 face-to-face) and references.
Generally the first two phone interviews are easy-peasy, conversations, good dialog. The next two are set format, situation/behavioral including the hypothetical build me a boolean string for X position. It seems like they have a set format and everyone sings from the same hymn sheet and you'll get asked the same question two or three times.
I'm very interested in working with Amazon, but interested to see if they truly embrace autonomy within a team. I like structure, but definitely not micromanagement.